1. Field of the Invention
This invention relates to the harvesting of grain and seed crops of the kind that are conventionally harvested by means of a combine harvester. More particularly, the invention relates to systems, methods and apparatus for harvesting such crops.
2. Description of the Prior Art
The applicant herein has already disclosed a novel method of and apparatus for harvesting grain and seed crops that provide an alternative to the use of conventional combine harvesters. In this regard, reference is made to U.S. Pat. No. 5,794,423 issued on Aug. 18, 1998; U.S. Pat. No. 5,795,222 issued on Aug. 18, 1998; and U.S. Pat. No. 5,873,226 issued on Feb. 23, 1999; all of these patents having been assigned to McLeod Harvest Inc. and are referred to collectively in the following description as “the McLeod patents.”
A conventional combine harvester operates by carrying out all of the harvesting steps in the field on a continuous basis. The crop plants are cut, the cut plants are threshed to separate grain (or seeds such as peas, etc.), chaff and (inevitably) weed seeds from the stalks, the grain is then cleaned by separating it from the chaff and weed seeds, the grain is delivered to a waiting collection vehicle, and the stalks, chaff and weed seeds are returned to the field. The disadvantages of this are that (a) combine harvesters are very expensive to purchase and to operate; (b) they are not very efficient at cleaning the grain, so some grain is lost and/or further grain cleaning is required; and (c) chaff and weed seeds are returned to the field, so that their economic value is lost and weeds proliferate.
The concept underlying the systems disclosed in the above patents is that, instead of attempting to carry out all of the harvesting steps in the field, only the step of threshing and removing stalks is carried out, and the remaining product (a mixture of grain, chaff and weed seeds—referred to by the coined word “graff”) is collected and transported to a fixed grain cleaning site. The advantage of this is that the harvesting equipment may be less complicated and expensive than a conventional combine harvester, the cleaning of the grain may be carried out more efficiently at a fixed site, the economic value of the chaff and weed seeds may be realized, and the need for herbicides is reduced (because the weed seeds are collected rather than being returned to the field).
It has been found that this system is extremely effective, but inconveniences have been encountered in that graff has proven to be a difficult material to handle and process. Since graff contains a large percentage of chaff, it is bulky for its weight and it is quite fibrous in composition. Unlike grain collected by a combine harvester, graff does not easily “flow” from containers and it is difficult to move by conventional means, such as augers, because it bridges or binds within itself and does not flow internally to replace material that has been removed from the bottom of a container or pile of the material. In general, it can be said that graff tends to pack, clump, bridge, rat-hole and bind, rather than flow smoothly. This causes problems not only when the graff is stored in silos or the like before it is processed, but also causes difficulties of material flow within the harvesting device and transportation vehicles.
Moreover, graff is difficult to store because, if stored in the open, it tends to blow away and also to spoil if it gets wet. However, if stored in a container, it is difficult to remove for the reasons mentioned above.
Additionally, there is a need to improve the overall efficiency of the system generally and to improve the manner in which individual components operate in order to increase the economic competitiveness of the system with conventional harvesting systems.